Superconductivity in TlBi${}_2$ with a large Kadowaki-Woods ratio

In this article, the superconducting and normal state properties of TlBi${}_2$ with the AlB${}_2$-type structure were studied by the resistivity, magnetization and specific heat measurements. It was found that bulk superconductivity with $T_C$ = 6.2 K emerges in TlBi${}_2$, which is a phonon-mediated $s$-wave superconductor with a strong electron-phonon coupling ($\lambda$${}_{ep}$ = 1.38) and a large superconducting gap (${\mathrm{\Delta }}_0$/$k_B{T}_C$ = 2.25). We found that the $\rho$($T$) exhibits an unusual $T$-linear dependence above 50 K, and can be well described by the Fermi-liquid theory below 20 K. Interestingly, its Kadowaki-Woods ratio $A\mathrm{/}{\gamma }^2$ [9.2$\times$10${}^{-5}$ $\mu \mathrm{\Omega }$ cm(mol K${}^2$/mJ)${}^2$] is unexpectedly one order of magnitude larger than that obtained in many heavy Fermi compounds, although the electron correlation is not so strong.